@feezor,

Typically when the devices disconnect like this, it is the result of a simple disconnect from the TP-Link Cloud.

Usually, this can be remedied with a simple restart or manual replugging. Does this cause the device to come back online and be controllable in either app?

Can you control the device from the Kasa App while you are connected to the same wireless network as the device?

If you cannot, there is something that is preventing your smart plug from communicating with other devices on your local network, such as a device isolation setting.

If you can see the plugs, try disconnecting from your Wi-Fi and controlling the devices from your mobile network.

I have also seen reports from some users that similar behaviors were fixed once they changed the default DNS server of their network to a common service such as Cloudflare or Google.